Generally, in a process for detecting a metal plate member, it is only possible to judge whether a defect is present and to determine its position if it is present in most case. However, it is more important to obtain quantitative information such as a size and a profile shape of the defect of the metal plate member to be used as an important basis for evaluating a health status of a metal plate and guiding the reparation and maintenance of the metal plate.
With the increasingly strict requirements on the safety of the metal plate member, there are needs to determine the profile shape of the defect, to image the defect with high precision, and to visualize a detection result of the defect.
In the related art, an ultrasonic guided wave has the following features: low attenuation, far propagation distance, 100% coverage of the thickness of the metal plate member a sound field, easy adjustment of a guided wave mode, etc., and guided wave detection with omni-directional magneto-acoustic transducers for an area surrounded by a transducer array from multiple angles can provide more abundant and accurate information of the defects for high-precision imaging of the defects.
However, a strong degree of scattering occurs when the guided wave encounter the defects, an influence and effect of scattering takes a dominant position, the scattering effect may generate more artifacts in a defect image re-established by a traditional guided wave imaging method, resulting in blind regions of the detection, which seriously affects location and imaging accuracy of the defects of the metal material member. In addition, the operation is not simple and convenient, and the efficiency is low.